Promising zintl-phase thermoelectric compound SrAgSb

Zintl-phase thermoelectric materials have garnered a lot of attention because of their intrinsic electron-crystal and phonon-glass structures. In this work, a series of ZrBeSi-type Zintl-phase compounds (SrAgSb, EuAgSb, and EuCuSb) were prepared, and their band structures and thermoelectric properties were investigated. The peak ZTs of SrAgSb, EuAgSb, and EuCuSb reach ∼0.5, ∼0.35, and ∼0.3 at 773 K. The carrier concentration of SrxAgSb was subsequently optimized by Sr self-doping. The increased Sr content suppresses the intrinsic hole concentration and leads to decreased total thermal conductivity. Together with the comparable power factor, a peak ZT of ∼0.6 was achieved at 773 K for Sr1.01AgSb and Sr1.02AgSb. The discovery of these ZrBeSi-type Zintl-phase thermoelectric materials provides a new family for exploring higher ZT.